1. Field of the Invention
This invention relates to condenser apparatus for collecting a mixture of high- and low-boiling point components and, more particularly, to a condenser with extremely high collection efficiency which can be hermetically sealed under either high or low temperatures.
2. Description of the Related Art
Methods of quantitative analysis such as gas chromatography can be used to measure the amounts of volatile components in a sample of material. The sample is heated in a containment chamber and the evolved volatile products are condensed and collected for subsequent analysis. Often the volatile products that are condensed have a very wide range of boiling points, so that the condenser apparatus used must be capable of operation over a very wide range of temperatures. High temperatures are required in the transport line between the containment chamber and the inlet to the condenser to prevent condensation of the high-boiling-point components in the line. Extremely high collection efficiencies are required for accurate analysis, so that the condenser is required to have a large amount of interior surface area in relation to the amounts of volatiles being collected. Because of the volatility of the components being collected, the condenser must be capable of being hermetically sealed after the completion of the collection phase of the procedure. The components employed for hermetic sealing must be capable of withstanding a combination of high and low temperatures as well as resisting damage by aggressive solvents.
Such a condenser apparatus as has been described above is necessary for the successful determination of the NMP content in prepreg by gas chromatography measurements. A satisfactory condenser would be able to operate at extremely high collection efficiencies with solvent mixtures (vapor, fluid, and solids) of widely different volatilities and high solvent powers. Various areas of the condenser would have to operate at temperatures ranging from greater than 500.degree. F. down to cryogenic temperatures. It would a great advantage if the condenser apparatus were easy to assemble and disassemble and to operate trouble-free even with condensed solid phases present. It would be additionally advantageous if the decanting of liquid condensates for subsequent analysis and the cleaning of the condenser in preparation for re-use were extremely easy procedures. Other desirable features would include the capability of quantitating sub-milligram amounts of condensed material quickly and with a high degree of accuracy. Finally, the use of materials that render the condenser very easy and inexpensive to construct, and that assure an operating life of many hundreds of cycles, would be another valuable feature. Some representative examples of the related art are briefly described and discussed below.
U.S. Pat. No. 1,798,032 to Rice describes a method and apparatus for removing superheat from steam, testing for suspended material, and condensing the steam for analysis.
U.S. Pat. No. 2,687,185 to McChesney describes a method and apparatus for obtaining condensate from vapor while avoiding contamination by gases present in the vapor.
U.S. Pat. No. 3,487,692 to Cook, Jr. describes a method and apparatus for sampling refrigerated mixtures of volatile liquids without fractionation of the samples. The apparatus described is not a condenser, but is designed to heat samples at constant volume with varying temperatures and pressures without affecting any phase change. The apparatus is not designed to operate under dynamic flow conditions.
U.S. Pat. No. 3,824,167 to Oswin et al describes an apparatus for detection and quantitative measurement of a select gas in a gaseous medium, such as alcohol in the breath or carbon monoxide in the atmosphere. The device comprises intake and flow control means for the gas sample, and an electrochemical cell for detection.
U.S. Pat. No. 3,956,921 to Himes et al describes an apparatus consisting of a simple tubular condensing coil fitted with a throttling valve and connected to a reservoir and vacuum chamber. The apparatus can be used for sampling fluid materials over a given period of time from a moving fluid stream such as a flue gas from a chimney or stack.
U.S. Pat. No. 3,985,624 to Prevost et al describes a method and apparatus for continuous sampling of vaporized fractions of crude petroleum, especially in crude petroleum topping columns.
U.S. Pat. No. 4,137,773 Loncaric describes a method and apparatus for obtaining liquid samples from petroleum handling equipment without the danger of electrostatic discharge.
U.S Pat. No. 4,335,620 to Adams describes a temperature controlled sample carrier apparatus usable in liquid chromatography. The apparatus contains a heat transfer coil which is not used to effect any phase change of interior or exterior fluids.
None of the examples of related art described above provides a condenser which can be routinely connected and disconnected from a main apparatus, which can operate trouble-free even with condensed solid phases present, which allows the quantitative determination of sub-milligram amounts of condensed material quickly and with a high degree of accuracy, which is capable of gas tight operation at extremely high collection efficiencies with solvent mixtures of widely different volatilities and high solvent power, and from which easy decanting of liquid condensate for subsequent analysis is possible, with a simple procedure for cleaning in preparation for re-use.